Date: Wed, 27 Mar 2002 14:34:30 -0800 From: Terry Lambert <tlambert2@mindspring.com> To: Seth Hieronymus <sethh@principia.edu> Cc: freebsd-chat@freebsd.org Subject: Re: processor question Message-ID: <3CA248F6.3ACA39B@mindspring.com> References: <OE100msHHbbgCzQ50pF00005549@hotmail.com>
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Seth Hieronymus wrote: > Do processors use more power / produce more heat when they are doing > processing other than an idle loop? > > Just wondering. Depends on what happens in the idle loop. If the idle loop is a HLT or an ACPI reduction in the power settings on one or more devices, then yes, there is some reduction in the power used. The ACPI stuff is normally use when the machine is genuinely idle, rather than merely executing in the idle loop. Generally, the idle loops means that you have outstanding requests to hardware standing unstatisfied, and are waiting for an interrupt before you can do more work. Not all idle loops HLT the processor. The SMP stuff started out not HLTing the processor, do to SMP schedule lock holding issues. In genreal, the amount is going to be negligible, compared to the energy required to keep the hard drives or fans spinning. I always love to see the "Energy Star" logo come up on boot on my machines. It means that it took three times as much energy to manufacture them as they would have additioanlly used during their entire operational life, had they not been "Energy Star" -ified. I guess some people just like to pay extra for their electricity so that they can pay for it up front. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-chat" in the body of the message
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